Abstract

Background: Cyclin D1 (CCND1) plays a crucial role in cell cycle regulation and has been implicated in various cancers. As is well known, cancer is caused by the accumulation of detrimental variations in the genome. In this study, we shed light on the role of CCND1 in the diagnosis and progression of cancer and aimed to provide a comprehensive analysis of CCND1 across multiple cancer types, focusing on its expression, clinical correlations, DNA methylation status, prognostic implications, genetic alterations, and immune infiltration. Methods: Gene expression analysis of CCND1 was conducted across 33 cancer types using the TIMER, GEPIA, and UALCAN databases. Clinical parameters were investigated to assess their correlations with CCND1 expression. Methylation analysis was performed using the UALCAN and GSCA databases to investigate the relationship between CCND1 promoter methylation and gene expression and their association with survival. Immune infiltration and survival analyses were performed to explore the prognostic implications of CCND1 expression in various cancers. Statistical tests, such as the Cox proportional hazards model and the Kaplan-Meier analysis, were used to assess survival outcomes. Additionally, genetic alteration analysis was performed using the cBioPortal database to examine the prevalence and types of CCND1 alterations across different cancer types. Results: CCND1 expression was significantly elevated in 13 cancers compared to normal tissues, with distinct patterns observed across different cancer types. It is highly expressed in BLCA, CHOL, COAD, ESCA, GBM, HNSC, KIRC, PAAD, RRAD, READ, STAD, THCA, and UCEC. The investigation of clinical parameters revealed associations between CCND1 expression and factors such as age, gender, race, and cancer stage. The methylation analysis highlighted hypomethylation of CCND1 across the 13 selected cancer types. The survival analysis identified both favorable and unfavorable prognostic implications of CCND1 expression in different cancers and revealed that a high expression of CCND1 was associated with a poor prognosis in HNSC and PAAD, while a high expression of CCND1 was associated with a good prognosis in KIRC, STAD, THCA, and UCEC. In the immune infiltration analysis of various cancers, many statistically significant correlations were observed between the immune cell types and tumor purity. For example, in BLCA, neutrophils and dendritic cells showed statistically significant positive correlations and a negative correlation with macrophages. While in CHOL patients, none of the immune cell types showed a significant correlation. Similar statistical significance was observed in other cancer types, such as COAD, HNSC, GBM, KIRC, PAAD, PRAD, READ, and STAD, with different immune cell types. The genetic alteration analysis revealed that amplification was the predominant genetic alteration type in CCND1, with specific patterns observed in different cancer types. Conclusion: The findings of this study provide valuable insights into the role of CCND1 in cancer diagnosis and progression, and its potential for targeted therapies. CCND1 could be used as a potential diagnostic biomarker for the COAD, ESCA, KIRC, READ, STAD, and THCA stages. Furthermore, CCND1 could be used as a potential prognostic biomarker for HNSC, KIRC, and PAAD. Also, the correlation between CCND1 methylation and expression could be used as a potential diagnostic and prognostic biomarker for ESCA, HNSC, and STAD.